docs: def __perform_rest_call(self, requestURL, params=None, headers=None, restType='GET', body=None):
          """Returns the JSON representation of the response if the response
          status was ok, returns ``None`` otherwise.
          """
          auth, headers = self.__prepare_gprest_call(requestURL, params=params, headers=headers, restType=restType, body=body)
          if restType == 'GET':
              r = requests.get(requestURL, auth=auth, headers=headers, params=params)
          elif restType == 'PUT':
              r = requests.put(requestURL, data=body, auth=auth, headers=headers, params=params)
          elif restType == 'POST':
              r = requests.post(requestURL, data=body, auth=auth, headers=headers, params=params)
          elif restType == 'DELETE':
              r = requests.delete(requestURL, auth=auth, headers=headers, params=params)
          resp = self.__process_gprest_response(r, restType=restType)
          return resp